High-frequency electrical switch and contactor system



April 30, 1946. FRESE v 2,399,430

HICH FREQUENCY ELECTRICAL swITCH AND CoNTACToR SYSTEM Filed March 1, 1944 4 Sheets-Sheet l A fr0/wv y April 3o, 1946. J F, FRESE 2,399,430

HIGH FREQUENCY ELECTRICAL SWITCH AND CONTACTOR SYSTEM Filed March 1. 1944 4 Sheets-Sheet 2 -d INVENTOR- k Jun/ala@ g) @57m/bef,

,TFLLE-Ey J. F. FRESE April 30, 1946.

HIGH FREQUENCY ELECTRICAL SWITCH AND CONTACTOR SYSTEM 1944 4 Sheets-Sheet 3 Filed March l INVENToR. me/MV,

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April 30, 1946. J. F. FREsE 2,399,430

HIGH FREQUENCY ELECTRICAL SWITCH AND GONTACTOR SYSTEM Filed March l, 1944 4 Sheets-Sheet 4 EEE- 15 a7 i JQ-w y live/wok.

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Patented Apr. 30, 1946 UNITED STATES PATENT oFFlcE HIGH-FREQUENCY ELECTRICAL SWITCH AND CONTACTOR SYSTEM Joseph F. Frese, Baltimore, Md., asslgnor to The Monitor Controller Company, Baltimore, Md., a corporation of Maryland Application March 1, 1944, Serial No. 524,594

8 Claims.

My invention relates broadly to high frequency electrical apparatus and more particularly to a construction of high frequency potential equalizer for association with the contactors of electrical switches and stand-oil insulators in high frequency electrical systems. l

One of the objects of my invention is to provide an improved construction of coronafshield for high potential, high frequency electrical appara- A further object of my invention is to providel an improved construction of streamlined high potential, high frequency unit for improving electrical eiliciency in high frequency, high potential circuits by maintaining discharge losses at circuit connection or terminal positionsA at a minimum.

Other and further. objects of my invention reizer and contact system shielded thereby on line 6 6 of Fig. 3; Fig. 'I is a transverse sectional view through the device of my invention taken on line 1-1 of Fig. 4; Fig. 8 is a transverse sectional view taken on line 8-8 of Fig. 4; Fig. 9 is side elevational view of the shell of the potential equalizing device with parts broken away and iliustrated in section; Flg. l is a vertical sectional view taken on line III--III of Fig. 1l; Fig. 1l is a vertical sectional view taken on line II-II of Fig. 9; Fig. 12 is a horizontal sectional view taken on line I2--I2 of Fig. 9 looking in the direction of the arrows; Fig. 13 is a transverse sectional view taken on line I3-I3 of Fig. 9; Figs. 14, 15, 16 and l74are views showing the construction of contact holder or plug which is employed in the device of -my invention; Fig. 18 illustrates in side elevation the application of the potential equalizer of myl invention to a stand-off insulation with parts broken away and shown in section; and Fig. 19 is a plan view of the potential equalizer illustrated in Fig. 18.

Referring to the drawings in detail, reference character I designates an insulated support which may be a stand-0E insulator of suitable insulation material such as Micalex or glass mounted in any suitable manner. The end of the insulated support provides a mounting means for side in an improved construction of substantially j toroidal shaped high frequency unit which may be produced on a quantity production basis at relatively low cost embodying structural features of novelty set forth more fully in the specification hereinafter following by reference to the accompanying drawings, in which:

Figure 1 represents one application of the potential equalizing device of my invention showing the manner of using the device as a shield for the contact system of a high potential switch; Fig. 1A is an enlarged longitudinal sectional view illustrating the arrangement of the elements of the device of my invention at the instance of establishing electrical vcontact in the switch system; Tag. 2 is a view snowing the switch system of Fig. 1 in plan and schematically illustrating the actuator; Fig. 3 is an end elevation of the potential equallzing device of my invention looking in the direction of arrow A in Fig. 1; Fig. 4 is a side elevation of the device illustrated in Fig. 3 looking in the direction of arrow B; Fig. 5 is a longitudinal sectional view through the device of my invention online 5--5 of Fig. 4; Fig. 6 is a longitudinal sectional view through the potential equalthe high frequency, high potential voltage equalizing surface member which' consists of a substantially toroidal-shaped structure modified to substantially conform with the contour of the supporting insulator I. 'I'he high frequency, high voltage terminal unit comprises a pair of symo metrically arranged members which I have designated at 2 and 3, each apertured at 2a and 3a for the passage of the end of the insulated support I. 'I'he symmetrically arranged parts 2 and 3 may be formed from a sand casting of cast brass although other metallic material may be employed. The parts 2 and 3 which fit together along a central dividing axis are substantially hollow except for central diametrically extending portions represented at 2b and 2c, and 3b and 3c. The curvature of the two substantially hollow members 2 and 3 is such that the surfaces are formed on a minimum radius of three-fourths of an inch and the exposed surface is a minimum for operation at high voltages without appreciable corona or electrostatic discharge.

The substantially hollow members 2 land 3 each have relatively thin walls of the order of one- Y eighth of an inch which abut edge to edge as indicated at 2d and 3d forming a tight seam. The abutting edges 2d and 3d may be ground to fom;

a substantially invisible seam or coacting joint and they are subsequently secured to each other by a process of welding, brazing, soldering or other manner.

The roundedv and curved surface members 2 and 3 in the form illustrated in Figs. 1-17 in-` clusive are arranged for protecting an electrical contact of a high frequency switch and in this form of my invention the parts 2 and 3 are somewhat modiiied and elongated from true toroidal shape and recessed at the end, providing a pair -of substantially parallel extending portions forming a pocket-like enclosure at one end of the device for electrically shielding an electrical contact device. End portions 2c and 3c are provided with end recesses 2e and 3e which when aligned coact to form a substantially square recess having rounded corners. The solid portions 2b and 3b of the potential equalizing device integrally connect with inner wall portions 2h and 3h which unite edge to edge forming an abutting inner surface against which the outer surface of insulator I abuts. The edges 2h and 3h are centrally apertured at 4 to permit the introduction and passage of a securing bolt 5 having a head 6 and a screw threaded end 1. The insulated support I has a transverse aperture 8 therein through which bolt 5 after passing through lock washer 9 and aperture 4 extends, projecting centrally into the contact carrying plug I Il. The contact carrying plug Ill extends into the substantially square recess formed by the coacting portions 2e and 3e and is secured therein by engagement between screw threads II formed internally in the plug I and screw threads on the end of bolt 1. The assembly is effected by fastening the corona shield to the insulated support I before the tubular connector 22 is placed into the socket formed by coacting parts 2b and 3b. This permits connecting bolt to be passed through aperture 4 and engaged in threads II in plug III. Thereafter connector 22 is secured to the socket in the corona shield. The plug III serves as a holder for the contact element I2 which is mounted in the lug portion I4 of the plug as shown. 4The lug portion I4 is apertured and shaped at I5 for receiving the contact support I6 which is relatively adjustable in the contact holder in order to present a plane surface for contact by the face of the movable contact designated at I1 carried by switch arm I8. The adjustable contact I2 is maintained in position through spring member I9 which exerts pressure between the countersunk recess 20 in the contact holder III and the headed end 2I of the adjustable contact. Thus the adjustable contact I2 may be angularly shifted in that position in which good electrical contact is established as the movable contact I1 is broughtinto contacting relation therewith. To insure good electrical connection between the potential equallzing. device, the adjustable contact I2 and the electrical connector 22 which enters the socket formed by aligned semi-cylindrical recesses 2f and 3f, I provide a flexible strip-like connector 23 extending from a position beneath contact I2 into the grooved recess 24 beneath the solid portion 2c of the potential equalizer. A set screw 25 extends through the potential equalizer and clamps the connector strip 23 in position therein, thus establishing good electrical connection.

The electrical connector 22 is retained in the socket formed between the solid portions 2b and 3b of the potential equalizing device by set screw 26 which extends through a threaded aperture 21 in the solid portion 3b and engages the tubular member constituting the electrical connector 22.

In Figs. 1 and 2 I have shown one form oi actuator for the switch system with which the corona shield of my invention is associated. It will be seen that a panel structure 28 is provided from which the stand-off insulator I extends. The stand-ofi insulator I may be of Micalex, glass or other form of high frequency insulator and may be mounted in a socket member 29 which is cemented as represented at 30-in the socket member 3I suitably secured to the panel 29 by bolts 32. The switch actuator includes lever actuating mechanism 33 journaled in standards I4 extending from panel 28. The lever actuating mechanism is operated from shaft member 35 journaled in standards 36 supported from panel 29. Shaft 35 is controlled by an operating magnet shown generally as housed within casing 31. 'I'he operating magnet is arranged to angularly shift shaft 35 which initiates in operation power control switch indicated at 33 and time control mechanism indicated at 39 while imparting angular movement to the motion multiplying lever mechanism represented at 33. 'I'he switch 3l is generally oi the single pole single throw type for controlling a power supply circuit. The time control mechanism 39 is generally employed for controlling circuits to electron tubes or other devices where it is desirable to complete a circuit through resistors in predetermined time relation to the other functions carried out by the switch system o! my invention.

The principal reason for illustrating the potential equalizing device as formed as a substantially hollow body is to save weight and material which would otherwise be employed in constructing the potential equalizing device. When it is realized that the potential equalizer even for moderate voltage installations may have over-all dimensions of approximately 51/4 x 41/2 x 21/2", it will be appreciated that a solid mass of metal of this size will have appreciable weight which is substantially reduced by the shell-like contour of my invention.

In Figs. 18 and 19 I have shown my invention applied to a stand-oil! insulator by which conduits or electrical connectors shown at 40, 4I,42 and 43 are interconnected. Set screws 40a, 4Ia, 42a and 43a extend through one or the other oi' the shells 44 and 45 for clamping the tubes or electrical connectors 40, 4|, 42 and 43 in position. It will be observed that the sections 44 and 4l are symmetrical in the case of the stand-of! insulator application and not elongated as in the case of the electrical contact shield application. The coacting sections 44 and 45 are modified from true toroidal shape but are apertured centrally for the passage of the stand-oir insulator I therethrough. Bolt member 49 which passes through apertured internal end walls in the diametrically opposite sockets formed between the coacting members 44 and 45 serves to secure the potential equalizing device adjacent the end of the stand-of! insulator. I have shown connecting means for four electrical connectors but it will be understood that the stand-oil insulator may be employed for connec tion of but two electrical connectors in which event socket portions are omitted from the structure of the shells constituting the potential equalizing device.

The structure of the corona shield is such that substantial weight is saved, thereby making the structure useful as a stand-of! insulator without and clearance distance between the shield andthe contact armin systems where the corona discharge voltage has been in the range of 80,000

volts while flash-over has occurred in the range of 83,000 volts. The use of the corona shield has improved emciency of the system by allowing continuous operation without flash-over at high voltages. In some of my earlier tests of the structure described herein using a smaller radius of approximately 1/2" and a break and clearance distance between the shield and the contact arm of approximately 6"', audible and visible corona discharge started at about 50 kv. R. M. S. at 60 cycles. Flash-over occurred at 60 kv. R. M. S. at 60 cycles between the stationary contact I2 and the movable contact l1 on the movable contact arm 2l. The test was conducted at a barometric pressure of 30.04 in Hg and temperature of 19.0 C. and relative humidity of 36%. The earlier tests were made where the minimum radius of the potential equalizing surface was approximately 1/2" and break and clearance distance of approximately 6". When this minimum radius was corrected by enlarging it to approximately 2%" and increasing the break and clearance distance to approximately 8" as explained hereinbefore, a further series of tests showed audible and visible corona discharge starting at 80 kv. R. M. S. 60 cycles with actual flash-over occurring at 83 kv. R. M. S. 60 cycles. These tests were conducted using the device as a contactor. Other tests made when using the device as a stand-off insulator gave even higher readings than those s et forth above, as for example, certain stand-off insulator tests where visible and audible corona discharge started at 89 kv. R. M. S. 60 cycles and actual flash-over occurred at 93kv. R. M. S. 60 cycles. Accordingly, it will be seen that the structure of my invention provides very substantial protection both as a contactor device and as a stand-off insulator device.

The figures given above respecting the approximate 3/4" radius and approximate 8" break are for devices where the discharge voltage is in the range of 80,000 volts while flash-over 'voltage is in the range of 83.000 volts. When the discharge voltage is reduced it is possible to reduce the 'approximate radius of the parts of the corona shield to approximately 1/2" for approximate breaks of 6". The dimensions given are relative and are cited as examples of statistical data which I have `accumulated in the course of the research and development of my invention.

While Iw have described my invention in certain of its preferred embodiments, I desire that it be understood that modifications may be made and no limitations upon my invention are intended other than may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. A corona shield comprising in combination with an insulatedsupporting post, a pair of substantially hollow metallic shell members each apertured to fit over the end of said post and electrically connected edge to edge to form an equipotential surface, a socket recess formed intermediate the adjacent edges of said members at one end thereof, a circuit terminal extending into said socket recess, means extending through one of said members for securing said circuit terminal in the socket recess, and an electrical contact device carried by said members adjacent the opposite en'd thereof, said 4contact device being electrically shielded by said members.

2. An equi-potential surface device comprising in combination with a supporting post of insulation material, a pair of shell-like substantially hollow members mounted edge to edge and centrally supported by said post, said members being symmetrically recessed at one end for receiving an electric circuit terminal and being symmetrically recessed at the opposite end for receiving an `electrical contact device, said members projecting beyond the limits of said contact device and operating to electrically shield said contact device.

3. An equi-potential surface device comprising in combination with a post of insulation matey rial, a pair of substantially hollow shell-like members having means disposed centrally thereof for engaging said post, said members extending a greater distance beyond one side of said post g than beyond the other side of said post and forming a socket recess on said latter side for a circuit terminal and a socket recess on said former side for an electrical contact, a circuit terminal extending into said first mentioned recess, and an electrical contact support extending into said second mentioned recess, and means extending through one of said members for securing said circuit terminal in said first mentioned socket recess and securing said contact device in said second mentionedv socket recess.

4. An equi-potential surface device comprising in combination with a post of insulation material, a pair of substantially hollow shell-like members each having means engaging said post, said members being electrically connected'edge to edge to establish a streamlined surface projecting a greater distance on one side of said post than on the opposite side of said post, a socket recess formed in said members on the side which projects the shorter distance from said post for receiving a circuit terminal therein, a socket recess formed in said members at the opposite side of said post for receiving an electrical contact device mounted in said electrical contact support in a position substantially withinthe limits of the projecting end of said members.

5. An equi-potential surface device comprising in combination with a post of insulation material, a pair of substantially hollow shell-like members electrically connected edge to edge and supported by said post, said members forming va socket recess in one end thereof adjacent said post, an electrical circuit terminal projecting into said recess, means forsecuring said electrical circuit terminal therein, the opposite ends of said members being centrally recessed and forming a socket intermediate said last mentioned recessed end and said post, a contact holder having a plug-like portion extending into said last mentioned socket, a projection on said plug-like portion, and a contact carried by said projection in a position substantially within the limits of said members.

6. An equi-potential surface device comprising in combination with a post of insulation material, a pair of substantially hollow shell-like members electrically connected edge to edge and supported by said post, said members forming a socket recess in one end thereof adjacent said post, an electrical circuit terminal projecting into said recess, means for securing said electrical circuit terminal therein, the opposite ends of said members being centrally recessed and forming a socket intermediate said last mentioned recessed end and said post, a contact holder having a. plug-like portion extending into said last mentioned socket, a projection on said plug-like portion, and an angularly shiftable contact device carried by said projection and movable to selected planes substantially within the limits of said members.

'7. A corona shield comprising in combination with an insulated post, a pair of coacting metallic members connected edge to edge and supported by said post, said members each having rounded external surfaces formed on radii of not less than approximately 3A of an inch for voltages in the range of 80,000, said surfaces extending a greater distance on one side oi the supporting post than on the other side thereof and forming a pair of substantially parallel projecting electrically shielding surfaces, and a contact device supported by said coacting members and extending between said pair of projecting portions of said parallel projecting electrically shielding surfaces.

8. A corona shield comprising in combination with an insulated post, a pair oi coacti-ng metallic members connected edge to edge and supported by said post, said members each having rounded external surfaces, said surfaces extending a greater distance on one side of the supporting post than on the other side thereof and forming a pair of substantially parallel projecting electrically shielding surfaces, and a contact device supported by said coacting members and extending between said pair of projecting portions of said parallel projecting electrically shielding surfaces.

JOSEPH F. FRESE. 

